OPA454 Datasheet, PDF (22/36 Pages) Texas Instruments – High-Voltage (100V), High-Current (50mA) OPERATIONAL AMPLIFIERS, G = 1 Stable

OPA454
SBOS391 – DECEMBER 2007
PowerPAD THERMALLY-ENHANCED
PACKAGES
The OPA454 comes in SO-8 and HSOP-20
PowerPAD versions that provide an extremely low
thermal resistance (θ_JC) path between the die and the
exterior of the package. These packages feature an
exposed thermal pad. This thermal pad has direct
thermal contact with the die; thus, excellent thermal
performance is achieved by providing a good thermal
path away from the thermal pad.
TOP-SIDE PowerPAD PACKAGE
The OPA454 DWD, HSOP-20, PowerPAD package
has the exposed pad on the top side of the package,
as Figure 71b shows. The top-side thermal pad can
be used with commercially available heat-sinks and
moving air to dissipate heat. The use of an external
top-side heat-sink increases the effective surface
area of the package face, which increases convection
and radiation off the top surface of the package.
Top-side heatsinking also avoids unnecessary
heating of the printed circuit board (PCB), and
permits installation of other PCB components onto
the side opposite of the OPA454.
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BOTTOM-SIDE PowerPAD PACKAGE
The OPA454 SO-8 PowerPAD is a standard-size
SO-8 package constructed using a downset
leadframe upon which the die is mounted, as
Figure 71a shows. This arrangement results in the
lead frame being exposed as a thermal pad on the
underside of the package. The thermal pad on the
bottom of the IC can then be soldered directly to the
PCB, using the PCB as a heatsink. In addition,
plated-through holes (vias) provide a low thermal
resistance heat flow path to the back side of the PCB.
This architecture enhances the OPA454 power
dissipation capability significantly, eliminates the use
of bulky heatsinks and slugs traditionally used in
thermal packages, and allows the OPA454 to be
easily mounted using standard PCB assembly
techniques. NOTE: Because the SO-8 PowerPAD is
pin-compatible with standard SO-8 packages, the
OPA454 is a drop-in replacement for operational
amplifiers in existing sockets. Soldering the
bottom-side PowerPAD to the PCB is always
required, even with applications that have low power
dissipation. Soldering the device to the PCB provides
the necessary thermal and mechanical connection
between the leadframe die pad and the PCB.
Leadframe (Copper Alloy)
IC (Silicon)
Die Attach (Epoxy)
Mold Compound (Plastic)
Leadframe Die Pad
Exposed at Base of the Package
(Copper Alloy)
Die
Attach
External Heatspreader
Die Pad
Chip
Power Transistor
Board
Thermal
Paste
a) SO-8 PowerPAD cross-section view.
b) HSOP-20 PowerPAD cross-section view.
Figure 71. Cross-Section Views of a PowerPAD Package
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